Igmp Snooping; Configuration; Overview Of Igmp Snooping; Multicast Groups - 3Com 4200G 12-Port Configuration Manual

29
Overview of IGMP
Snooping

IGMP Snooping

Fundamentals
IGMP S
NOOPING
IGMP Snooping (Internet Group Management Protocol Snooping) is a multicast
control mechanism running on Layer 2 switch. It is used to manage and control

multicast groups.

When the IGMP messages transferred from the hosts to the router pass through the
Layer 2 switch, the switch uses IGMP Snooping to analyze and process the IGMP
messages.
Table 219 IGMP message processing on the switch
Received message
type Sender
IGMP host report Host
message
IGMP leave message Host
By listening to IGMP messages, the switch establishes and maintains MAC multicast
address tables at data link layer, and uses the tables to forward the multicast packets
delivered from the router.
As shown in Figure 79, multicast packets are broadcasted at Layer 2 when IGMP
Snooping is disabled and multicasted (not broadcasted) at Layer 2 when IGMP
Snooping is enabled.
Figure 79 Multicast packet transmission with or without IGMP Snooping
Multicast packet transmission Multicast packet transmission Multicast packet transmission Multicast packet transmission Multicast packet transmission Multicast packet transmission Multicast packet transmission Multicast packet transmission
without IGMP Snooping without IGMP Snooping without IGMP Snooping without IGMP Snooping without IGMP Snooping without IGMP Snooping without IGMP Snooping without IGMP Snooping
Video stream Video stream Video stream Video stream
Muliticast Muliticast Muliticast router Muliticast Muliticast Muliticast router Muliticast router Muliticast router
Video stream Video stream Video stream Video stream Video stream Video stream Video stream Video stream
Layer 2 Ethernet sw itch Layer 2 Ethernet sw itch Layer 2 Ethernet sw itch Layer 2 Ethernet sw itch
Video stream Video stream Video stream Video stream
Video stream Video stream Video stream Video stream
Multicast Multicast Multicast Multicast Multicast Multicast Multicast Multicast
Non- Non- Non-multicast Non- Non- Non- Non- Non-multicast Non- Non- Non- Non-multicast Non- Non- Non- Non-multicast
group member group member group member group member group member group member group member group member
group member group member group member group member group member group member group member group member group member group member group member group member group member group member group member group member
C
ONFIGURATION
Receiver
Switch
Switch
Video stream Video stream Video stream Video stream
Internet Internet Internet Internet Internet Internet Internet Internet
Muliticast Muliticast Muliticast router Muliticast router Muliticast router Muliticast Muliticast Muliticast router
VOD server VOD server VOD server VOD server
Layer 2 Ethernet sw itch Layer 2 Ethernet sw itch Layer 2 Ethernet sw itch Layer 2 Ethernet sw itch
Video stream Video stream Video stream Video stream
Video stream Video stream Video stream Video stream
Multicast Multicast Multicast Multicast Multicast Multicast Multicast Multicast
group member group member group member group member group member group member group member group member
Switch processing
Add the host to the corresponding
multicast group.
Remove the host from the multicast
group.
Multicast packet transmission Multicast packet transmission Multicast packet transmission Multicast packet transmission
with IGMP Snooping with IGMP Snooping with IGMP Snooping with IGMP Snooping
Video stream Video stream Video stream Video stream Video stream Video stream Video stream Video stream
Internet Internet Internet Internet Internet Internet Internet Internet
Video stream Video stream Video stream Video stream Video stream Video stream Video stream Video stream
Non-multicast Non- Non- Non- Non- Non-multicast Non- Non- Non- Non- Non- Non-multicast Non- Non-multicast Non- Non-
group member group member group member group member group member group member group member group member group member group member group member group member group member group member group member group member
VOD server VOD server VOD server VOD server